Advanced thermal-welding processes

The use of advanced thermal joining processes such as ultrasonic welding. 

The alternative methods next to sewing include adhesive bonding, conventional thermal (e.g., hot air and heated tool) welding, and advanced thermal (e.g., ultrasonic or laser) welding. These joining methods are the focus of this chapter. A general description of these processes, along with applicable substrates and applications, is provided in Table 13.1. 

A number of advanced thermal processes other than hot-air or heated-tool processes have been developed for the joining of garment materials. The most prominent are ultrasonic, dielectric, and laser welding. Because of equipment cost, required skill level, and relative inflexibility, these processes are used mainly in specialty applications. However, most garment manufacturers see broader application for these technologies in the future as the cost can be justified by the added-value propositions. 

Similar to conventional thermal welding, these advanced heating processes can be used to activate thermoplastic adhesives. However, the focus here will be on joining substrates without the use of an added adhesive material. 

The thermophysical properties of titanium alloys may also contribute to difficulty encountered during friction stir welding. Some numerical simulations of the FSW process indicate that low thermal diffusivity can contribute to the formation of advancing side wormhole or tunnel defects in friction stir welds the thermal diffusivities of titanium alloys are among the lowest of all metals. 

Ares, A.E. Gatti, I. P. Gueijman, S.F. Schvezov, C.E. (2009) Mechanical Properties of Zinc-Aluminum Alloys versus Structural and Thermal Parameters, Proceedings of MCWASP International Conference Modeling of Casting, Welding and Advance Solidification Processes - XII, Vancouver, Canada, June of 2009... 

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